ehamster.tex

数据挖掘中de一个算法 hamster的实例

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---------------------------------------------------------------------------
-- File    : control.e
-- Contents: customized hamster control class
-- Authors : Ilona Bl"umel and Christian Borgelt
-- History : 11.03.1999 file created
---------------------------------------------------------------------------
class CONTROL
inherit CLIENT
  redefine control
end
creation
  make

---------------------------------------------------------------------------
-- Methods
--------------------------------------------------------------------------- 
feature                   
control (hamster: HAMSTER) is   -- hamster control function (random)
local
  movecnt: INTEGER;             -- number of moves made
  turn   : INTEGER;             -- turn direction (left/right)
  d      : INTEGER;             -- dummy variable for results
do
  from
    movecnt := 0;               -- initialize the move counter
  until
    movecnt = 50                -- make 50 field to field moves
  loop
    if     hamster.get_x = 0    -- if we are at home (initial position),
    and    hamster.get_y = 0    -- drop all the corn we have
    then   d := hamster.drop(hamster.max_load);
    elseif hamster.get_corn > 0 -- if there is corn on the field
    then   d := hamster.take(hamster.max_load);
    end                         -- take as much as he can carry
    if hamster.get_look = hamster.wall  -- if the way is blocked
    or else random(4) <= 1      -- or just because it's funny (25%)
    then if random(2) <= 1      -- randomly choose a turn direction
         then turn := hamster.left;
         else turn := hamster.right;
         end                    -- (50% either way)
         from
           hamster.turn(turn);  -- turn the hamster
         until                  -- in the chosen direction
           hamster.get_look /= hamster.wall
         loop                   -- repeat turning the hamster around
           hamster.turn(turn);  -- until no wall blocks the way
         end
    end
    d := hamster.move;          -- move the hamster forward
    movecnt := movecnt +1;      -- and count the move made
  end
end  -- control

------------------------------------------------------------------------
end  -- CONTROL
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